The constructions known to the art consist mainly of a plate stiffened with a supporting structure, in which plate the electromagnets are mounted. Individual electromagnets are inserted into the plates with their open pole end (for instance threaded into it) and are connected to each other at the opposite pole end by a bridge.
Since it is desirable for the use of the magnetic beam and often required by the processing techniques, that the magnetic beam be as straight and level as possible, when overall dimensions are increased a stronger construction of the plate together with the supporting structure is required. The operating conditions, already severed due to mechanical rigidity reasons, as aforedescribed, in practice are more difficult because, depending upon use, the magnetic beams are subject to stress not only mechanically but above all electrically and, as a result, are exposed to significant temperature variations. In rest position, which means no current, the magnetic beam is cold. Depending on the applied contact pressure or current intensity, various high temperatures result.
Based on the current state of the art, it is almost impossible to build long magnetic beams, which means magnetic beams for large work widths, which are sufficiently stable regardless of temperature.
Based on the present state of the art, temperature related bending of magnetic beams of larger dimension are unavoidable. The size of such undesired deflections can reach more than 1 mm in the case of long magnetic beams and consequently can result in considerable inaccuracy for the process to be carried out with the aid of the magnetic beam.
Sometimes, cooling jets are incorporated as means to keep the temperatures and as a result the straightness constant. Other cooling methods are also available. Cooling systems are not only expensive but they also have to be considered as a poor means only to temporarily keep the heat conditioned deflections within somewhat acceptable limits.
Complete precision in the straightness of electromagnetic beams which are subject to various work loads or current intensities and temperature variations resulting therefrom can not be achieved with the present state of the art.